Nocturnal hemodynamic patterns differ substantially from daytime patterns in a variety of mammals including man. In patients with heart disease, these patterns could affect the incidence of morbid events which are known to occur in the morning. This project is designed to test the effectiveness of interventions which may ameloriate adverse effects of nocturnal hemodynamics. A Doppler echocardiographic study on patients with mitral regurgitation investigates morning rehydration effects on viscosity and cardiac functions.